Frequency hopping spread spectrum modulation and direct sequence spread spectrum modulation cordless telephone

Abstract

A wireless transceiver capable of selectively receiving and transmitting as a direct sequence spread spectrum system or as a frequency hopping spread spectrum system is disclosed. The system is particularly suitable for use in a cordless telephone system. The transceiver includes components for both direct sequence spread spectrum transmission and reception and for frequency hopping spread spectrum transmission and reception.

Description

BACKGROUND OF THE INVENTIONI. Field of the InventionThe invention relates generally to communications. In addition, the invention relates to wireless telecommunications including cordless telephones.II. Description of the Related ArtThe cordless telephone has become a popular consumer good. The cordless telephone allows a user to untether himself from a wired connection to his local telephone line. Typically, a cordless telephone is comprised of two units: a base unit and a handset both of which are transceivers. The base unit connects to the public switched telephone network typically using a standard RJ-11 connector. The base unit provides a wireless connection to a handset. The handset is capable of receiving and transmitting signals over a wireless link to the base unit. The use of the wireless link allows the handset to communicate with the base unit.Many cordless telephones operate as a time division duplex (TDD) system. In time division duplex, the base unit and the handset a...

AI Technical Summary

Benefits of technology

In a cordless telephone system employing direct sequence spread spectrum modulation, increasing the data transmission rate requires increasing the bandwidth of the transmitted RF signal. Increasing the bandwidth requires changes to the radio frequency (RF) hardware (e.g., wider filter bandwidths, wider bandwidth power amplifiers). In addition, as the bandwidth of the DSSS signal increases to occupy a larger fraction of the frequency range allocated to cordless telephones, the probability of encountering interfering signals increases while the available number of channels for use with cordless telephones decreases. However, employing frequency hopping spread spectrum modulation allows for an increased data transmission rate within the currently available bandwidth. Such higher data transmission rates may be required, for example, for data communications such as are typically employed by personal computers communicating via the Internet.

Problems solved by technology

In addition, as the bandwidth of the DSSS signal increases to occupy a larger fraction of the frequency range allocated to cordless telephones, the probability of encountering interfering signals increases while the available number of channels for use with cordless telephones decreases.

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